Many solid antiperspirant compositions have been described in the chemical and cosmetic literature. These compositions generally tend to fall into one of two classes: emulsion sticks and suspensoid sticks. Emulsion sticks contain a solution of the antiperspirant active incorporated into the stick via an emulsion. Although emulsion sticks may be desirable in certain respects, they tend to be unstable, have poor aesthetics (e.g., are overly hard, greasy or sticky), and leave a visible residue on the skin after use. Suspensoid sticks contain the powdered antiperspirant active suspended in the stick without the use of water or an emulsion. While suspensoids tend to be stable, they may be brittle and hard and, more importantly, they tend to leave an unsightly white chalky residue on the skin after application. This residue is not only aesthetically displeasing to the user, but can also soil clothing. It has now been discovered that when certain non-volatile paraffinic hydrocarbon fluids, such as mineral oils or branched chain C.sub.16 -C.sub.68 hydrocarbons, are incorporated into water-free suspensoid antiperspirant stick compositions, those compositions exhibit excellent antiperspirant efficacy and aesthetics, while leaving reduced visible residue on the skin of the user. The present invention may also provide a benefit in terms of improved delivery and substantivity of perfumes included in the compositions.
Although mineral oil and some volatile branched chain hydrocarbons have been taught for use in certain types of deodorant compositions, they have not heretofore been taught for use in substantially water-free suspensoid type stick compositions. For example, mineral oil has been used in water-containing emulsion type deodorant sticks (see, e.g., U.S. Pat. No. 3,255,082, Barton et al., issued Jun. 7, 1966), in aerosol deodorants (e.g., U.S. Pat. No. 3,968,203, Spitzer et al., issued Jul. 6, 1976), and in deodorant creams (see, e.g., U.S. Pat. No. 4,083,956, Shelton, issued Apr. 11, 1978). See also European Patent Application 28,853, Beckmeyer et al., published May 20, 1981 (mineral oil as a non-volatile emollient in liquid antiperspirant compositions).
U.S. Pat. No. 4,425,328, Nabial, issued Jan. 19, 1984, describes deodorant sticks containing an antiperspirant active, a volatile cyclic silicone emollient, a clay suspending agent, and an activator for the clay. These compositions may optionally include emollients, such as 2-ethyl hexyl palmitate. U.S. Pat. No. 4,265,878, Keil, issued May 5, 1981, describes emulsion type deodorant sticks containing an antiperspirant active dispersed in a solid matrix which includes a volatile water-insoluble liquid. Useful volatile liquids include cyclic polysiloxanes and volatile paraffinic hydrocarbons, such as branched chain C.sub.15 or lower hydrocarbons. U.S. Pat. No. 4,229,432, Geria, issued Oct. 21, 1980, describes the use of certain waxy materials (such as straight and branched-chain paraffinic hydrocarbon waxes) to keep active components dispersed in an antiperspirant stick. U.S. Pat. No. 4,724,139, Palinczar, issued Feb. 9, 1988, describes antiperspirant sticks which include 5-80% of a volatile isoparaffin liquid, 5-60% of a water-insoluble wax, and 8-60% of a particulate antiperspirant active. It is to be emphasized that the Keil and Palinczar products tend to be unacceptable in terms of visible residue on the skin after use, high temperature stability and/or aesthetics.